Boring bar holder



Febf7; 1950. A. M. THOMAS BORING BAR HOLDER Fil Jan. 17, 1948 INVENTOR AZbefiZM Thomas (m 79 11mm ATTORNEY Patented Feb. 7, 1950 UNITED STATES ATENT OFFICE BORING BAR HOLDER Albert M. Thomas, New York, N. Y.

Application January 17, 1948, Serial No. 2,851

Claims. 1

My invention relates to a machine tool and in particular to a universal boring-bar holder, as for use in performing boring operations on a lathe.

It is an object of the invention to provide an improved device of the character indicated.

It is another object to provide an improved universal boring-bar holder having features of rigidity and ease of adjustment for a wide number of uses.

Other objects and various further features of the invention will be pointed. out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, a preferred form of the invention:

Fig. 1 is a partly broken plan view of a universal boring-bar holder incorporating features of the invention;

Fig. 2. is a view in elevation of the holder of Fig. 1;

Fig. 3 is a sectional View taken in the plane 3-3 of Fig. 2; and

Fig. 4 is an exploded View in perspective showing the several parts of the structure of Figs. 1 and 3.

Briefly stated, my invention contemplates an improved boring-bar holder utilizing a base plate having a substantial area of supporting contact with a bar-holding member. The base plate and the bar-holding member may be. relatively rotatable about a swivel axis, and the bar-holding member may include a. bar opening which may be slightly removed from the swivel axis. A clamping jaw may be formed integrally with the barholding member to define the bar-holding opening, with the jaw overstanding the swivel axis. Securing means such as a bolt may pass through the base plate, the main body of the bar-holding member, and the jaw, so that in one operation a boring bar may be secured in the bar-holding member and the bar-holding member may be secured to the base plate. If desired, the securing means may include an enlarged head or other means for engagement with a T-slot in a compound rest, so that the single operation of tightening the securing means may additionally serve to lock the base plate to the compound rest or the like of the machine to which my tool is adapted.

Referring to the drawings, my invention is shown in application to a boring-bar holder to be supported on the compound rest 5 of a lathe. My novel holder includes a base-plate member 6,

a bar-holding member a, and securing means. The securing means may include a bolt 8 extending through the base plate 6 and the holding member I and serve for the pivotal retention of members 5-? together. The area of supporting contact between members 6'l is preferably extensive, and in the form shown the abutting surfaces at 9 extend for the full annulus between the bolt 8 and the relatively wide outer diameter of the base plate 6. The bar-holding member l is preferably integrally formed with an overhanging jaw [0 extending to define a boring-bar opening H providing extensive longitudinal support for a boring bar l2; the. jaw l0 may include a part it through which the bolt 8 may extend for clamping purposes.

The underside of the. base plate 6 is preferably formed so as to include a projecting part [4 to engage walls of the T- or other slot in which my tool is mounted, as in the compound rest 5. The head end of the bolt 8 may be enlarged to engage the. inner recesses of the slot in the compound rest 5, or as in the form. shown it may carry an enlarged plate l5 for such engagement. The plate i5. is shown to include a. projecting part In, also in engagement with the walls of the slot in the compound rest 5. A nut I! may be threaded to the bolt 8 above the jaw H). for easy access when making an adjustment.

It will be noted that with the described arrangement, a single operation, namely a setting of the nut I 7, is all that is needed in order to secure. the bar I2 to the holder element 1, to secure the holder element 1 to thebase plate 6, and. to secure the base plate 6 to the compound rest. If desired, appropriate graduations may be inscribed on the base plate and on the bar-holding member 1, as at I8, to indicate the adjusted relative positioning of these elements and hence the angularity of the boring bar l2.

For fast boring and reaming operations, and in a preferred form, my universal boring-bar holder is constructed so that the boring-bar opening ll may be aligned with the axis of the lathe spindle, and one end of the boring bar [2 is formed with a diametrically extending opening fioatingly to receive a tool, such as the tool 19. By forming each end of the tool 55 with a cutting surface 20, and preferably also with a land 2!, it will be understood that high-speed boring and reaming operations may be readily performed. In Fig. 1, a tube 22 is being bored to a finish diameter D. Once the cutting edges 20 have made an initial cut into the tube 22, the lands 21 may ride on the 3 finish-bored surface 23 and thus guide the tool I9 for further stages of the boring cut.

The other end of the boring bar l2 may be provided with another tool slot or opening for holding a tool such as the tool 24 at an angle other than normal to the bore axis, and set-screw or other securing means (not shown) may anchor the tool 24 to the bar I2. In like manner, setscrew or other securing means (not shown) may anchor the tool H3 or any similar tool in the diametral slot, but it will be understood that such securing means would be relaxed for the floating type of boring or reaming operation which has been described.

It will be appreciated that I have described a relatively simple device for the universal support of a boring bar, as on the compound rest of a lathe. My boring-bar holder has been extremely useful, in that setting-up time has been reduced to a minimum by the employment of only one securing element, namely, the nut 11 to secure the boring bar to the holder element I, the holder element 1 to the base plate 6, and the base plate 6 to the compound rest 5.

While I have described my invention in detail for the preferred form shown, it will be understood that modifications may be made within the scope of the invention as defined in the appended claims.

I claim:

1. In a device of the character indicated, a bar holder and a base plate relatively rotatable about a swivel axis and having abutting surfaces of substantial area said base plate including means on its underside to guidingly engage a compound rest or the like, said bar holder and said base plate being relatively rotatable when said surfaces are in abutment with each other, said bar holder having a bar-receiving opening off said swivel axis and including a jaw overstanding said swivel axis for clamping a bar in said bar-receiving opening, and means spanning said jaw and said base plate and including means to engage a compound rest or the like for simultaneously clamping a bar in said bar-receiving opening and said bar holder against said base plate,

, whereby upon relatively slight relaxation of said last-defined means, said holder and said base plate may be angularly adjusted relative to each other and the bar may also be adjusted in said holder and all said elements may be secured to a compound rest or the like.

2. In a device of the character indicated, a bar holder and a base plate having substantial abutting areas and being relatively rotatable on a swivel axis while said areas are in abutment, said bar holder having a bar-receiving opening off said swivel axis and perpendicular thereto and including a clamping jaw overstanding said swivel axis, and securing means including a bolt member passing through said base plate and said jaw and including means to engage a slot in a compound rest or the like, whereby upon securing said bolt member said base plate may be positioned in said slot and said bar holder may be pivotally set with respect to said base plate and said jaw may be clamped upon a bar.

3. A device according to claim 2, in which the slot to be engaged is a T-slot and in which said base plate includes projecting elements to engage opposite walls of said T-slot.

4. In a device of the character indicated, a boring bar having a diametrically extending opening toward one end thereof for fioatingly receiving a diametrically extending tool, a bar-holding member having an opening to receive said bar, a base plate having a substantial generally circular area angularly adjustably to receive said barholding member, and securing means including a bolt passing through said base plate and said jaw for securing said base plate and said bar-holding member and said bar in a single securing operation.

5. In a device of the character indicated, a generally circular base plate including a downwardly and diametrically extending projecting portion to be guided by walls of an undercut slot in a compound rest or the like, a bar holder in abutment with said base plate, said base plate and said bar holder abutting each other on circularly symmetrical surfaces of substantial area, an integral bar-holding jaw on said bar holder, and bolt means including means to engage an undercut side of the slot and passing through said base plate and through said bar holder and through said jaw, whereby said base plate may always be maintained in a given alignment with the compound rest or the like and yet, in a single adjust. ing operation, said bar holder may be longitudinally and angularly positioned and a bar may be positioned and secured.

ALBERT M. THOMAS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 849,414 Mueller Apr. 9, 1907 1,314,911 Stephenson Sept. 2, 1919 1,351,632 Engels Aug. 31, 1920 

